Antimicrobial Susceptibility of Streptococci Most Frequently Isolated from Czech Dairy Cows with Mastitis

Abstract

the aim was to investigate the antimicrobial susceptibility of most frequently isolated streptococci from czech dairy herds. A total of 3,719 quarter milk samples were collected and cultivated between January 2017 and June 2018 from cows with clinical or subclinical mastitis from 112 farms. only one isolate of each species, collected from the same farm per six-month period, was included in the susceptibility testing. the susceptibilities of Streptococcus uberis (163 isolates) and S. dysgalactiae (25 isolates) to 10 antimicrobials (penicillin -pen, amoxicillin/clavulanic acid -Amc, ceftiofur -eft, clindamycin -cli, gentamicin -Gen, streptomycin -str, trimethoprim/sulfamethoxazole -SXT, enrofloxacin -ENR, tetracycline -TET, rifampicin -RIF) from 9 groups were determined by measuring their minimum inhibitory concentrations. the percentages of resistant S. uberis isolates to the antimicrobials were as follows: tet (63.2%), str (52.1%), cli (30.1%), and rif (2.5%). intermediate susceptibility was found to rif (63.2%), pen (35%), enr (2.5%), eft (1.8%), and Amc (1.2%). All the S. uberis isolates were susceptible to Gen and sXt (100%). however, only 6.7% of S. uberis isolates were susceptible to all tested antimicrobials, and 38.7% of isolates were multidrug resistant (≥ 3 groups of antimicrobials). All the S. dysgalactiae isolates were susceptible to pen, Amc, eft, Gen, sXt, and enr (100%). resistant S. dysgalactiae isolates were found to tet (60%), str (28%), cli (12%), and intermediate to tet (24%) and rif (20%). sixteen percent of S. dysgalactiae isolates were multidrug resistant. the relatively high occurrence of (multiple) resistance, relative to mastitis pathogens, highlights the importance of monitoring this condition in dairy herds.

Gordonia species as a rare pathogen isolated from milk of dairy cows with mastitis

“…A certain parallel can also be seen with trimethoprim/sulfamethoxazole, which are representatives of the group of potentiated sulfonamides previously used (even in the intramammary form) for the treatment of mastitis and many other primary and secondary bacterial infections of dairy cows in the Czech Republic. Multidrug resistance was detected in 23.8% of our isolates of Gordonia sp., which is a lower frequent rate than that observed in the most prevalent gram-positive bacteria causing mastitis in the Czech Republic ( S. uberis ), with 38.7% of its isolates 29 .…”

“…In our intensive recent study of antimicrobial resistance of mastitis-causing gram-positive bacteria from the same intake area/catchment area, clindamycin was the antimicrobial with the third highest rate of resistant isolates of Streptococcus sp. 29 . A certain parallel can also be seen with trimethoprim/sulfamethoxazole, which are representatives of the group of potentiated sulfonamides previously used (even in the intramammary form) for the treatment of mastitis and many other primary and secondary bacterial infections of dairy cows in the Czech Republic.…”

“…s r.o., Prague, CZ) and incubated aerobically at 37 ± 1 °C for 42–48 h. The growth of individual cultures was evaluated semiquantitatively, and the results were reported as sporadic (+) to heavy (++++) growth. On plates with mixed bacterial cultures, i.e., containing 2 or maximally 3 different bacterial species, the most frequent colony-forming agent was regarded as the dominant species, i.e., as the dominant pathogen 29 . Plates containing more than three different bacterial species were classified as contaminated without further identification of bacterial species.…”

Characterization of Gallibacterium anatis Isolated from Pathological Processes in Domestic Mammals and Birds in the Czech Republic

“…In the laboratory, all samples were processed within 24 h of collection. Cultivation methods involved using meat peptone blood agar (MPBA) and Endo agar (EA) (both from Trios, s. r. o., Prague, Czech Republic), and plates were aerobically incubated at 37 ± 1 °C for 24–48 h. The growth of cultures was semi-quantitatively evaluated, and the results were reported as sporadic (+) to heavy (++++) growth [ 18 ]. Plates containing multiple bacterial cultures from organs lacking a microbiome were classified as contaminated without further identification.…”